Zinc base alloy



' Patented Aug. 7, 19 45 umrso s'rArss PATENT orr'lcs ZINC BASE AL or Iw .Edward S. Bunn, Rome,'N. Y., asslgnor to Revere 'Copper and BrassIncorporated, Home, N. Y., a corporation of Maryland No Drawing;Application June is. 194:.

- Serial No. 491,059

4 Claims. (01. 75-178) My invention, which relates to zinc base alloysand has among its objects the production of a zinc base 'alloy ofimproved characteristics, will be best understood from the followingdescription, the scope of the invention being more particularly. pointedout in the appended claims.

As will be well understood by those skilled inthe art, pure zinc informs commercially available has a rather low tensile strength, but goodductility. Although capable of beinghot and cold worked this metal hasthe defect that it sell anneals when cold worked and thus, asdistinguished from most cold workable metals, cannot be hardzinc even inrelatively small amounts markedly increases the tensile strength of thezinc without unsatisfactorily decreasing its ductility for most usesofthe resulting alloy. This increase in tensile strength is greater thanif copper alone is added. For example, adding 1% copper to zinc willincrease its tensile strength in the hot rolled conditionfrom 17,000 to29,000 pounds per square ened and its tensile strength increased by coldworking. Further, pure zinc ,is subject to grain" growth'as it ages,particularly in hot and humid situations, causing it gradually to losewith age most of its ductility coupled with -a serious reduction in itstensile strength. For example, hot rolled zinc having a tensile strengthof 17,000 pounds per square inch and a ductility represented by anelongation of 45% in 2 inches will,

when subjected to the standard test for determiningthe effect of age onzinc and its alloys, namely, subjecting it to moist steam at 95 C. for10 days, have, its tensile strength reduced to 11,000 pounds per squareinch and its elongation in 2 inches reduced to about 2%, the latterindicating almost total loss of ductility.

To attempt to cure these defects of zinc by adding other elements-to itcommonly results in either so great a sacrifice of its ductility as torender it unsuitable for most uses or, if its tensile strength andductility are originally satisfactory when such elements are added toit, its being subjectto a serious loss of one or the other, or both, asthe zinc ages, and further commonly makesv the zinc subject tointergranular corro-v sion and unstable in respect to dimensions as itages.

in zinc to an unsatisfactory degree in respect to use of the zinc inmost situations can be substantially-prevented by adding to it smallamounts 1 inch, its ductility represented by an elongation of 45% in 2inches remaining substantially un-- changed, but adding'i).2% telluriumor selenium, or a mixture of the .two, with 1% copper will furtherincrease the tensile strength of the zinc in the hot rolled condition to34,000 pounds per square inch, while decreasing its elongation in 2inches only to about 35%, which latter is a very satisfactory ductilityfor most uses of the resulting alloy.

Satisfactory results in the above respects will be secured within theranges of 0.1 to 5% copper and.0.2 to 0.8% metal of the group consistingof tellurium and selenium. Further, the resulting alloys arecommercially hot and cold workable by usual mill processes, and by themcan be hot or cold rolled into sheets, these alloys being much morereadily worked, particularly'when cold, than binary zinc-copper alloys,which latter cannot be commercially cold rolled when the amount ofcopper exceeds about 3 or 4 The improved worked 4 0 However, applicanthas found that grain growth alloys have a resistance to shock or impactloading very much superior to that of zinc or binary zinc-copper alloys,making them satisfactory for uses where such property is ofsignificance, as it usually is; The tensile strength of the improvedalloys likewise is much higher than that of pure zinc and markedlyhigherthan thatv of binary zinc-copper alloys. Still further, the'ductility of the improved alloys is satisfactorily high for most uses,as is alsotheir stability in respect to maintaining good tensilestrength and ductility as they age. For any ordinary use of the improvedalloys they are satisfactorily stable with age in respect to maintainingtheir dimensions and freedom from warping,and have good resistance tointergranular corrosion. With amounts of 1.5% or more copper they do notself anneal when cold worked. Best results in respect to securing hightensile strength combined with good a ductility are secured within therange of 2.25 to 5% copper. properties of the alloys best results willbe had when the amount of metal of the group isnot substantially morethan 50% of the amount of copper. 1

It will be understood that, within the scope In respect to securing goodall around or the appended claims, other elements may be added to theimproved alloy for modifying its properties or imparting additionalproperties, so long as the characteristics imparted by addin copper andmetal of the group to the zinc are not destroyed;

I claim:

1. Zinc base alloys containing, approximately,

0.1 to 5% copper, 0.02 to 0.8% substance of the group consisting oftellurium and selenium, the 10 balance being substantially zinc.

EDWARD S. BUNN.

